Mapquest's navigation app already offers a slew of features that we've come to expect from a worthy GPS app, but it has recently seen an update that brings Skyhook's hybrid positioning engine into the mix. This engine not only uses satellites for global positioning, but it also judges accurate location by using nearby WiFi networks (Google Location does this as well - but Skyhook utilizes their own proprietary magic and claim it's more accurate).
Even though Google and Skyhook haven't always played nice, the addition of the Skyhook engine in Mapquest really does make it a worthy competitor to our beloved Google Navigation (some may say that it already was). It includes a swarm of the same features - like voice search, turn-by-turn voice navigation, auto-reroute, and walking or driving direction.
Mapquest is free in the Android Market, so give it a whirl and let us know how it compares to Google Navigation in your area.